In a liquid crystal display device, a thin-film EL (electroluminescence) display device, an organic EL display device or the like, an amorphous silicon film has been conventionally mainly used as a semiconductor film that functions as a channel layer of a TFT (thin-film transistor) which is a semiconductor device.
In recent years, however, attention has been focused on an oxide semiconductor film mainly composed of an In—Ga—Zn-based composite oxide (hereinafter also referred to as “IGZO”) as the aforementioned semiconductor film, because of the advantage of higher carrier mobility as compared with the amorphous silicon film.
For example, Japanese Patent Laying-Open No. 2008-199005 (PTD 1) discloses that this oxide semiconductor film mainly composed of IGZO is formed by a sputtering method using a target.
In addition, Japanese Patent Laying-Open No. 2004-091265 (PTD 2) discloses an oxide sintered body mainly made of indium and including tungsten, as a material suitably used when forming an oxide semiconductor film by the sputtering method and the like.